Foamed materials (foams) have been used to secure image display members, display members, and other optical members (e.g., cameras and lenses) to predetermined regions (e.g., cabinets), where the image display members are to be secured to image display devices such as liquid crystal displays, electroluminescence displays, and plasma displays; and the display members and other optical members are to be mounted typically to so-called “cellular phones”, “smartphones”, and “personal digital assistants”. Examples of the foamed materials to be used include low-expansion (high-density) microcellular urethane foams having a closed-cell structure; foams prepared from high-expansion (low-density) polyurethanes via compression molding; and polyethylene foams including closed cells and having an expansion ratio of about 30. Specifically, examples of the foamed materials to be used include a gasket including a polyurethane foam having a density of 0.3 to 0.5 g/cm3 (see Patent Literature (PTL) 1); and a sealant for electrical/electronic devices, where the sealant includes a foam structure having an average cell diameter of 1 to 500 μm (see PTL 2).
However, with decreasing thicknesses of products to which the optical members (e.g., image display devices, cameras, and lenses) are to be mounted, clearances of portions at which the foamed materials are used tend to significantly decrease. With decreasing clearances, the foamed materials have to have smaller thicknesses. However, conventional foamed materials fail to offer sufficient impact absorption when having such smaller thicknesses. Accordingly, demands have been made to provide foamed sheets for use typically in “smartphones” and other electrical/electronic devices with display members, where, when the electrical/electronic devices are dropped off typically onto the ground, the foamed sheets absorb impacts upon collision with the ground and eliminate or minimize the failure of the display members.
Independently, shock absorbing sheets are used for eliminating or minimizing the failure typically of display members in electronic devices such as personal computers (PCs), tablet PCs, personal digital assistants (PDAs), and cellular phones. As the electronic devices increase in functionality, the shock absorbing sheets are laminated with other members (e.g., thermally-conductive layers) and integrated into the electronic devices. Further reduction in thickness of the electronic devices demands further reduction in thickness of members such as the shock absorbing sheets to be used in the electronic devices. This demands reduction in thickness of, or disuse of, an adhesive layer upon lamination of the shock absorbing sheets with the other members.